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Flexible petrol pipe

Description: No Description Available.
Date: July 1, 1921
Partner: UNT Libraries Government Documents Department

High efficiency of seaplanes

Description: A table is presented which includes data for calculating the index of efficiency. The author uses this data to conclude that seaplanes cannot be considered inferior to terrestrial airplanes.
Date: August 1, 1921
Creator: Pegna, G.
Partner: UNT Libraries Government Documents Department

An investigation on the effect of raked wing tips

Description: This investigation was carried out by request of the United States Air Service in the wind tunnel of the Massachusetts Institute of Technology. The results are here published by the National Advisory Committee for Aeronautics as it is thought that they may be of general interest. Wings of the R.A.F. 6 section are tested with various angles of rake, and it is found that although rake has very little effect, a positive or negative rake of 30 degrees is the best.
Date: November 1, 1921
Creator: Norton, F. H.
Partner: UNT Libraries Government Documents Department

Measurements of rudder moments on an airplane during flight

Description: Tests indicated that: 1) C airplanes with two struts are extremely susceptible to aileron maneuvers, slight alterations of the aileron sufficing to compensate great unequalized moments; 2) great unequalized moments can be produced or neutralized by the unequalized alternation of the angle of attack below the outer and inner struts. Adjustment below the outer strut is the more effective of the two. 3) When a load of bombs is suspended beyond the center of the airplane, below the wings, the bombs need not be dropped simultaneously. 4) The propeller wash of a wide open engine has considerable influence on the position and operation of the elevator. The elevator is more susceptible in flight with the engine running than in gliding flight. 5) Adjustable tail planes are not advisable for D airplanes, nor for the C type, but they are, on the other hand, to be recommended for large size and giant airplanes in which the center of gravity changes during flight. 6) The aileron values obtained by wind tunnel measurements are about 10 percent too low, though otherwise applicable. For the elevator, the results of such measurements should be taken as mean values between flight with the engine running and gliding flight.
Date: January 1, 1921
Creator: Heidelberg, Ing V
Partner: UNT Libraries Government Documents Department

Nomenclature for aeronautics

Description: The purpose of the Committee in the preparation and publication of this report is to secure uniformity in the official documents of the government and, as far as possible, in technical and other commercial publications. This report supersedes all previous publications of the Committee on this subject.
Date: January 1, 1921
Partner: UNT Libraries Government Documents Department

A new dynamometer brake

Description: The mechanism here described belongs to the class of dynamometer brake in which the motive power is transformed into heat in the brake itself. This mechanism was invented by the writer for the purpose of measuring forces in which the two factors, torque and speed, vary within broad limits, the mechanism itself being of simple construction and of still simpler operation.
Date: September 1, 1921
Creator: Segre, Marco
Partner: UNT Libraries Government Documents Department

A new method of testing in wind tunnels

Description: Now, in existing wind tunnels, using a horsepower of 100 to 300, the models are generally made to a 1/10 scale and the speed is appreciably lower than the speeds currently attained by airplanes. The Reynolds number realized is thus 15 to 25 times smaller than that reached by airplanes in free flight, while the ratio of speed to the velocity of sound is between a third and three quarters of the true ratio. The necessary increases in either the diameter of the wind tunnel or the velocity of the airstream are too costly. However, the author shows that it is possible to have wind tunnels in which the Reynolds number will be greater than that now obtained by airplanes, and in which the ratio of the velocity to the velocity of sound will also be greater than that realized in practice, by employing a gas other than air, at a pressure and temperature different from those of the surrounding atmosphere. The gas is carbonic acid, a gas having a low coefficient of viscosity, high density, and a low ratio of specific heat. The positive results of using carbonic acid in wind tunnel tests are given.
Date: August 1, 1921
Creator: Margoulis, W
Partner: UNT Libraries Government Documents Department

Preliminary calculation of cylinder dimensions for aircraft engines

Description: It is extremely important in building aircraft engines to determine the requisite cylinder dimensions as accurately as possible, in order that the weight required for a given power shall not be excessive. This report presents a calculation method that depends on the air requirement of the fuel.
Date: September 1, 1921
Creator: Schwager, Otto
Partner: UNT Libraries Government Documents Department

Large German airship stations

Description: No Description Available.
Date: August 1, 1921
Creator: Sabatier, J.
Partner: UNT Libraries Government Documents Department

The law relating to air currents

Description: In the subdivided wing section profile, the diagram of the current is entirely changed and the harmful formation of eddies is avoided through premature deflection. Pressure equalization does not occur between the upper and under sides. This report presents a discussion of the various laws relating to wing design with the conclusion being that lift increases with more acute angles of attack.
Date: March 1, 1921
Partner: UNT Libraries Government Documents Department

The law relating to air currents

Description: Discussed here are the aerodynamics of a subdivided wing section. The emphasis is upon the increase of lift with more acute angles of attack. Also discussed are wind tunnel tests of the relations among wind resistance, lift, angle of attack, and velocity.
Date: March 1, 1921
Partner: UNT Libraries Government Documents Department

Loads and calculations of army airplanes

Description: By comparing airplanes of known strength that have resisted all the usual and even extreme air loads with those that under like conditions were found to be insufficiently strong, the researchers, aided by scientific investigations, developed standards which are satisfactory for the calculation of airplane structures. Given here are standards applicable to loads on wing trusses, load factors for use in stress analysis, load factors required in sand testing, loads on control surfaces, loads on wing ribs, loads on landing gear, and rigidity of materials.
Date: February 1, 1921
Creator: Stelmachowski, Ing
Partner: UNT Libraries Government Documents Department

A high-speed engine pressure indicator of the balanced diaphragm type

Description: This report describes a pressure-measuring device especially adapted for use in mapping indicator diagrams of high-speed internal combustion engines. The cards are obtained by a point-to-point method giving the average of a large number of engine cycles. The principle involved is the balancing of the engine cylinder pressure against a measured pressure on the opposite side of the metal a diaphragm of negligible stiffness. In its application as an engine indicator the phase of the engine cycle to which a pressure measurement corresponds is selected by a timing device. The report discusses briefly the errors which must be avoided in the development of an indicator for light high-speed engines, where vibration is serious, and outlines the principles underlying the design of this instrument in order to be free of such errors. A detailed description of the instrument and accessories follows together with operating directions.
Date: January 1, 1921
Creator: Dickinson, H C & Newell, F B
Partner: UNT Libraries Government Documents Department

On the resistance of the air at high speeds and on the automatic rotation of projectiles

Description: Here, the laws governing the flow of a compressible fluid through an opening in a thin wall are applied to the resistance of the air at high speeds, especially as applied to the automatic rotation of projectiles. The instability which we observe in projectiles shot into the air without being given a moment of rotation about their axis of symmetry, or without stabilizing planes, is a phenomenon of automatic rotation. It is noted that we can prevent this phenomenon of automatic rotation by bringing the center of gravity sufficiently near one end, or by fitting the projectile with stabilizing planes or a tail. The automatic rotation of projectiles is due to the suction produced by the systematic formation of vortices behind the extremity of the projectile moving with the wind.
Date: April 1, 1921
Creator: Riabouchinski, D
Partner: UNT Libraries Government Documents Department

The coupling of engines

Description: This report examines the idea of coupling numerous engines together to turn a single propeller, which the author feels would free aircraft design from the problems of multi-engine and propeller design.
Date: April 1, 1921
Creator: Boccaccio, Paul
Partner: UNT Libraries Government Documents Department

Crippling strength of axially loaded rods

Description: A new empirical formula was developed that holds good for any length and any material of a rod, and agrees well with the results of extensive strength tests. To facilitate calculations, three tables are included, giving the crippling load for solid and hollow sectioned wooden rods of different thickness and length, as well as for steel tubes manufactured according to the standards of Army Air Services Inspection. Further, a graphical method of calculation of the breaking load is derived in which a single curve is employed for determination of the allowable fiber stress. Finally, the theory is discussed of the elastic curve for a rod subject to compression, according to which no deflection occurs, and the apparent contradiction of this conclusion by test results is attributed to the fact that the rods under test are not perfectly straight, or that the wall thickness and the material are not uniform. Under the assumption of an eccentric rod having a slight initial bend according to a sine curve, a simple formula for the deflection is derived, which shows a surprising agreement with test results. From this a further formula is derived for the determination of the allowable load on an eccentric rod. The resulting relations are made clearer by means of a graphical representation of the relation of the moments of the outer and inner forces to the deflection.
Date: October 1, 1921
Creator: Natalis, FR
Partner: UNT Libraries Government Documents Department

The drawing of experimental curves

Description: This report presents a discussion of how to determine the location of a line or surface from experimental data. What we desire to know practically is the number of ordinates required to obtain a certain probable precision in drawing a line or surface.
Date: July 1, 1921
Creator: Norton, F. H.
Partner: UNT Libraries Government Documents Department

Design of wind tunnels and wind tunnel propellers II

Description: This report is a continuation of National Advisory Committee for Aeronautics report no. 73. The variations in velocity and direction of the wind stream were studied by means of a recording air speed meter and a recording yawmeter. The work was carried on both in a 1-foot diameter model tunnel and in a 5-foot full-size tunnel, and wherever possible comparison was made between them. It was found that placing radial vanes directly before the propeller in the exit cone increased the efficiency of the tunnel to a considerable extent and also gave a steadier flow.
Date: January 1, 1921
Creator: Norton, F. H. & Warner, Edward P.
Partner: UNT Libraries Government Documents Department

Aneroid investigations in Germany

Description: Report presenting an experiment of aneroid development and a theoretical study of the equilibrium of forces acting on the vacuum box.
Date: October 1921
Creator: Hersey, M. D.
Partner: UNT Libraries Government Documents Department